How to Read a Resistor: Color Bands and Values

Resistor markings tell you a component’s nominal resistance, usually in ohms (Ω), and how closely its actual value should match that rating. Learning to decode the bands helps you identify a part before installing it, check a circuit diagram, or compare a component with a measured value. You need good light and, if the bands are hard to see or you want to verify the part, a digital multimeter.

What You’ll Need

A resistor with visible color bands, or a clear photo of it
Good lighting; a magnifier can help with small or faded bands
A resistor color-code chart or the digit key below
A digital multimeter for an independent measurement

Step-by-Step

Look for the band pattern. Hold the resistor so you can see all its bands. Most through-hole resistors have four, five, or six color bands. A noticeable gap before the final band often marks the reading direction: begin at the end where bands are grouped more closely. The separated band is commonly the tolerance band. If spacing is unclear, turn the resistor and decode both possible directions; one should produce a plausible value and tolerance.
Identify the number of bands. On a four-band resistor, the first two bands are significant digits, the third is the multiplier, and the fourth is tolerance. On a five-band resistor, the first three bands are significant digits, the fourth is the multiplier, and the fifth is tolerance. A six-band resistor uses the same arrangement as a five-band type, with a sixth band that usually indicates the temperature coefficient. Do not mistake the extra band for another digit.
Convert the digit colors. In order, black means 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, and white 9. For a four-band part, combine the first two digits. For a five- or six-band part, combine the first three. For example, red and violet give 27; brown, black, and red give 102.
Apply the multiplier. The next band tells you how much to multiply the digit value by. Black is ×1, brown ×10, red ×100, orange ×1,000, yellow ×10,000, green ×100,000, and blue ×1,000,000. Gold means ×0.1 and silver means ×0.01. Some specialized codes include additional multiplier colors, so consult a chart if the band is gray, white, or otherwise unfamiliar. Keep the result in ohms, then convert to kilo-ohms (kΩ) or mega-ohms (MΩ) if convenient.
Read the tolerance band. Tolerance is the allowed variation around the nominal value, not another part of the resistance calculation. Common codes include brown for ±1%, red for ±2%, gold for ±5%, and silver for ±10%. No tolerance band often means ±20% for a standard four-band code, but do not assume this for an unusual or specialized component. Read the component’s documentation if the exact specification matters.
Calculate the nominal resistance. Combine the digits and multiply by the multiplier. For example, a four-band resistor with yellow, violet, red, and gold bands has digits 4 and 7, a ×100 multiplier, and ±5% tolerance: 47 × 100 = 4,700 Ω, or 4.7 kΩ ±5%. The tolerance means the actual resistance may fall within 5% above or below 4,700 Ω under the conditions specified for the part.
Use a chart for extra specifications. If there is a sixth band, it generally gives the temperature coefficient, often expressed in parts per million per degree Celsius (ppm/°C). This indicates how much resistance can change as temperature changes. Its code depends on the band color and standard used, so look it up rather than treating it as a tolerance or digit. For surface-mount resistors, markings are often printed numbers instead of colored bands; use an SMD code reference for those.
Verify with a multimeter if needed. Switch off and unplug the circuit before testing. For the most reliable reading, remove the resistor or disconnect one lead from the circuit; other components connected across it can affect the measurement. Set the meter to resistance (Ω), choose an appropriate range if it is not autoranging, and touch one probe to each lead. Avoid touching the bare metal probe tips during the measurement, since your body can influence readings of high-resistance parts. Compare the display with the nominal value and tolerance.

Common Mistakes

Reading from the wrong end: Starting at the tolerance end shifts every role. Look for the wider gap and check whether the result makes sense.
Confusing similar colors: Red and brown, or orange and red, can look alike in dim light or on a discolored part. Improve the lighting, use a magnifier, and compare the reading with a meter or parts list.
Counting the multiplier as a digit: The multiplier follows the significant-digit bands. A resistor marked with four bands does not have three digits.
Forgetting units: 1,000 Ω equals 1 kΩ, and 1,000,000 Ω equals 1 MΩ. Converting the unit does not change the resistance.
Treating tolerance as exactness: A 4.7 kΩ resistor with ±5% tolerance is not guaranteed to measure exactly 4.7 kΩ. Normal measurement conditions and meter accuracy also matter.
Measuring in a powered circuit: Never use resistance mode on an energized circuit. Power it down first; stored charge in capacitors can also affect readings or create a hazard.

Tips

Write the result in both forms, such as 4,700 Ω and 4.7 kΩ, to reduce unit mix-ups.
Photograph a hard-to-read resistor and zoom in, but remember that camera lighting can distort color.
Check the circuit’s parts list or schematic when the decoded value seems unusual. The design may use a less common value, or the component may have been replaced.
Keep the resistor’s power rating separate from its resistance value. Color bands generally do not tell you how much power it can safely dissipate; use the part marking or datasheet.
Use the correct resistor type and rating when replacing one. Matching resistance alone may not be enough if tolerance, power, temperature behavior, or physical size matters.

Troubleshooting

The colors are too faint to identify: Clean dust from the component gently, improve the lighting, and use magnification. If the body is cracked, charred, or badly faded, do not rely on the color code; consult the circuit documentation or replace it with a correctly specified part.

Neither direction gives a sensible value: Recount the bands and check whether you have a four-, five-, or six-band part. It may be a specialized code, a surface-mount resistor, or a component other than a standard resistor. Look up its manufacturer marking or measure it out of circuit.

The multimeter reading is unstable or far off: Confirm the circuit is unpowered, disconnect one lead, and make sure the probes contact clean metal. Check the meter’s range and battery, then repeat the test. Capacitors or other parallel paths can distort an in-circuit reading; a damaged resistor may also have drifted beyond tolerance.

The meter shows “OL” or a very high value: The selected range may be too low, the probe may not be making contact, or the resistor may be open. Select a higher range or use autoranging, check the connections, and test the isolated component again.

Frequently Asked Questions

Which end of a resistor do I read first?

Start at the end where the bands are closest to the edge, usually opposite a separated tolerance band. If spacing is ambiguous, check both orientations against a color chart and the likely resistance range.

What does a gold band mean?

Gold commonly means a ×0.1 multiplier when it is in the multiplier position, or ±5% tolerance when it is the final band. Its role depends on where it appears.

What do the letters K and M mean on a resistor?

They commonly stand for kilo-ohms and mega-ohms: K means thousands of ohms, and M means millions. Printed surface-mount codes can use letters in other ways, so check the code format before interpreting them.

Can I read resistance with a multimeter while the resistor is installed?

You can try only with the circuit switched off, but connected components may create alternate paths and give a misleading value. Disconnecting one lead usually provides a more dependable reading.

Do resistor bands show its power rating?

Usually not. The power rating depends on the resistor’s type and construction; check its part number, datasheet, or circuit documentation rather than inferring it from the color code.

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